Digital integrator

ABSTRACT

A DIGITAL INTERGRATOR INCLUDES A CIRCULAR TABLE HAVING A TOOTHED SURFACE MOUNTED FOR ROTATION ABOUT A CENTRAL AXIS. A TOOTHED WHEEL IS ROTATABLY SUPPORTED FOR ENGAGEMENT WITH THE TABLE TEETH AND FOR DISPLACEMENT RADIALLY OF THE AXIS OF ROTATION OF THE TABLE. THE TABLE SURFACE IS FORMED WITH CONCENTRIC CIRCULAR TOOTHED TRACKS INTERCONNECTED BY SPIRAL TOOTHED TRANSFER TRACKS. THE TEETH OF THE VARIOUS TRACKS ARE ARRANGED SO THAT ROTATION OF THE TOOTHED WHEEL WHEN ENGAGED WITH ANY TRACK IS PROPORTIONAL TO THE DISTANCE OF SUCH WHEEL FROM THE TABLE AXIS. IN ONE EMBODIMENT, THE TABLE SURFACE HAS A CENTRAL ZONE WHICH IS DEVOID OF TEETH AND THE MAIN TOOTHED WHEEL IS COUPLED BY A SLIDE TO AN AUXILIARY WHEEL HAVING TEETH ENGAGEABLE WITH A GUIDE PLATE WHEN THE MAIN WHEEL IS IN THE CENTRAL ZONE, WHEREBY THE MAIN WHEEL IS GUIDED BACK TO THE APPROPRIATE TRACK OF THE TABLE ON LEAVING THE CENTRAL ZONE. ADJUSTMENT OF THE RADIAL DISTANCE OF THE MAIN WHEEL FROM THE AXIS OF ROTATION IS EFFECTED BY CENTRALLY PIVOTED FINGERS CIRCUMFERENTIALLY SPACED AROUND THE TBALE. EACH FINGER NORMALLY HAS ONE END ENGAGED IN A FIXED CIRCULAR GUIDE TRACK, ITS OTHER END ENGAGING A GROOVE IN THE SLIDE OVER A LIMITED PORTION OF THE CIRCULAR PATH OF THE FINGER. ACTUATION OF A CONTROL ELECTROMAGNET CAUSES THE ONE END OF THE FINGER TO BE TEMPORARILY DEFLECTED INTO EITHER OF TWO LATERAL GUIDE TRACKS WHICH DIVERGE FROM THE CIRCULAR GUIDE TRACK AND THEN REJOIN IT. THE RESULTING MOVEMENT OF THE OTHER END OF THE FINGER INDEXES THE SLIDE A GIVEN RADIAL DISTANCE.

Nov. 16, 1971 R, BGUlN ETAL DIGITAL INTEGRATOR 4 Sheets-Sheet 1 Filed Oct. l, 1969 NOV. 16, 1971 R, BGUIN ETAL DIGITAL INTEGRATOR 4 Sheets-Sheet 2 Filed OCt. 1, 1969 Nov. 16, 1971 R. SEGUIN ETAL 3,620,090

DIGITAL INTEGRATOR Filed Oct. l, 1969 4 Sheets-Sheet f11 United safes Patent o1 ace U.S. Cl. 74-31 9 Claims ABSTRACT F THE DISCLOSURE A digital intergrator includes a circular table having a toothed surface mounted for rotation about a central axis. A toothed wheel is rotatably supported for engagement with the table teeth and for displacement radially of the axis of rotation of the table. The table surface is formed with concentric circular toothed tracks interconnected by spiral toothed transfer tracks. The teeth of the various tracks are arranged so that rotation of the toothed wheel when engaged with any track is proportional to the distance of such wheel from the table axis. In one embodiment, the table surface has a central zone which is devoid of teeth and the main toothed wheel is coupled by a slide to an auxiliary wheel having teeth engageable with a guide plate when the main wheel is in the central zone, whereby the main wheel is guided back to the appropriate track of the table on leaving the central zone. Adjustment of the radial distance of the main wheel from the axis of rotation is effected by centrally pivoted ngers circumferentially spaced around the table. Each finger normally has one end engaged in a fixed circular guide track, its other end engaging a groove in the slide over a limited portion of the circular path of the finger. Actuation of a control electromagnet causes the one end of the nger to be temporarily deflected into either of two lateral guide tracks which diverge from the circular guide track and then rejoin it. The resulting movement of the other end of the finger indexes the slide a given radial distance.

This invention relates to a digital integrator.

Mechanical integrators are known which comprise a rotatable table and a wheel which is driven by contact with the surface of said table and is movable radially of the table. In such a device, the wheel is in frictional contact with the table surface and a certain relative slip may obviously occur.

This slip can be limited if appropriate materials are selected, but it cannot be completely eliminated. To obviate a rapid increase in errors as a result of their summation, it is therefore essential to provide a control system which, for example, will initiate frequent rezeroing operations.

These known devices are analogue integrators and the possibility of slip makes it impossible to use them in numerous applications where accurate and reliable agreement is required between the data transmitted to the device and the data delivered by the device.

Mathematical apparatus is also known for continuously securing from a variable input a prescribed output which is dependent in value upon the value of the input, but which bears a predetermined, non-linear relation to the input. Such apparatus comprises a rotatable table having a single spiral gear on its surface, said spiral gear meshing permanently with a radially sliding follower. Since the surface comprises just one spiral track, the apparatus is simply a variable ratio spiral cam gear of limited angular movement, the use of which is very limited.

One of the objects of the invention is to provide a digi- 3,620,090 Patented Nov. 16, 1971 tal integrator of unlimited rotation so that much more general problems can be solved, and in this new apparatus this is rendered possible by the fact that a single rotatable toothed input table enables different output variables to be obtained for a given input variable, the output variables being selected from different predetermined linear functions of the input variable, the changeover from one linear function to another also being obtained in accordance with the predetermined non-linear function of the input variable.

In accordance with the invention there is provided a digital integrator comprising a table having a surface provided with teeth, means mounting the table for rotation about an axis, a toothed wheel having teeth for meshing with the teeth of the table surface, and means mounting the toothed wheel for engagement with the table surface and for displacement radially of the axis of rotation of the table, wherein the improvement comprises a plurality of concentric circular toothed tracks of different diameters formed on the table surface and at least two toothed transfer tracks inclined in opposite directions formed on the table surface, the transfer tracks interconnecting the concentric tracks thereby permitting passage of the toothed wheel from one of the circular tracks to another, the teeth of the circular tracks and of the transfer tracks being so arranged that rotation of the toothed wheel engaged on the tracks remains constantly proportional to the distance of the toothed wheel from the axis of rotation of the table both on the circular tracks and along the transfer tracks.

The permanent well-defined engagement between the toothed wheel and the plate eliminates al1 the systematic errors arising in known mechanical integrators as a result of incorrect positioning of the wheel. Furthermore, the clearances required between the moving parts do not affect the accuracy of the device so that its manufacture is simple and uncomplicated.

In a preferred embodiment, the transfer tracks are devised for radial displacement of the wheel leaving a plot on the table surface corresponding exactly to a `true spiral (Archimedean spiral).

The digital integrator according to the invention is in fact suitable for the control of curve plotters, the table being driven at a constant speed and the toothed wheel driving an output shaft at a perfectly predetermined speed according to the diameter of the circular track it follows.

With such apparatus, the data delining the curve to be plotted may be referred to the variations of the components along two axis of the speed of a plotter, the variations corresponding to the changeover of the wheel from one circular track to another. Such data relating to the accelerations may be much less numerous than the data which would deiine the curve by the coordinates of its successive points, or by components of the speed.

With these and other objects in view which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawings, in which:

FIG. 1 is a plan view of a first embodiment of digital integrator;

FIG. 2 is an elevation of the embodiment of FIG. 1;

FIG. 3 is a partial section on the line 3 3 of FIG. 1, some of the movable elements being shown in different positions in the two views;

FIG. 4 is a partial section on the line 4-4 of FIG. 3;

FIG. 5 is a diagrammatic view of the teeth of the plate of the integrator shown in FIG. 1, and shows just a part of the plate in plan view and on an enlarged scale;

FIG. 6 is a section of the line 6 6 of FIG. 7, showing a guide plate;

FIG. 7 is a plan view of the guide plate;

FIGS. 8, 9 and l() are diagrammatic views of variant embodiments of digital integrators.

The digital integrator apparatus illustrated in FIGS. 1 to 7 comprises a circular table 1 mounted for rotation by means of ball-bearings 2 and 3 on a sleeve 4 screwed to a frame 5. A shaft 6 keyed to the table 1 allows the latter to be rotated (FIG. 3). The table 1 comprises a top part 1a and a bottom part 1b which are stepped where they engage one another (FIG. 3). These two parts 1a and 1b together define a circular groove housing a ring 7 of circular section which forms a pivot for twelve small plates r fingers 8 housed in twelve radial slots 9 distributed uniformly over the circumference of the table 1 (FIGS. 1 and 3).

Each nger 8 has a bottom end portion 10 which during rotation of the table moves in a guide groove 24 formed in a base plate 11 secured to the frame. The fingers 8 can perform a limited rocking movement on the pivot formed by the ring 7 as shown in FIG. 3.

The frame comprises two side columns 12 and 13 supporting a shaft 14 whose axis is coplanar with the axis of the shaft 6 and perpendicular thereto.

The shaft 14, which is of hexagonal section, has its ends mounted in ball-bearings so that it can rotate freely with respect to the frame 5.

A rod 15 is disposed parallel to the shaft 14 between the columns 12 and 13 and a slide 16 is supported by the rod 15 and by the shaft 14 (FIG. l).

The slide 16 comprises two identical casings 17 and 18 disposed at its ends and interconnected by a plate 19. Casing 17 contains a main toothed wheel or pinion 20 mounted slidably on the shaft 14 and secured so as to rotate therewith as a result of the hexagonal section of its bore. The casing 18 houses an auxiliary pinion 21 mounted slidably on the shaft 14 and also secured for rotation therewith as a result of the hexagonal section of its bore. The pinions 20 and 21 radially project from the top and bottom surfaces of the casings, which have openings for this purpose.

The casings 17 and 18 are also mounted slidably on the rod 15, and the plate 19 has on its bottom surface teeth formed by seven arcuate grooves 22a, 22k, 22C, 22d, 22e, 22j and 22g, in which top end portions 23 of the fingers 8 engage momentarily on rotation of the plate 1 (FIG. 3).

The guide groove 24 in base plate 11 constitutes cam means and comprises a circular track 24a having the same diameter as the ring 7 which acts as a pivot for the fingers 8, so that the latter occupy the vertical position shown in FIG. 3 while their bottom ends follow the circular track 24a.

Over a sector visible in FIG. 4, the groove 24 also comprises two lateral tracks 24b and 24e which diverge from a radius 25 to progressively reach lateral end positions on a radius 26, positions being situated on either side of the circular track 24a and being offset by a distance D in relation to the axis of the latter (FIG. 4).

A control electromagnet 28 disposed along the radius 25 comprises a magnetic plunger 29 having a central arm and two lateral arms, the latter carrying two energization windings 30 and 31 (FIG. 3). On rotation of the table 1, the fingers 8 move past the magnetic plunger 29 and end surfaces 32 of the lateral arms of the magnetic plunger are inclined to cause the finger 8 moving in front of said pole surfaces to pivot in a direction depending upon the state of energization of the electromagnet. If the finger is attracted to the bottom arm of the plunger as a result of energization of the winding 3l. this pivoting movement brings the bottom end of the small plate into engagement with the outer track 24b. If the finger is attracted to the top arm as a result of energization of the winding 30, it pivots in the opposite direction and its bottom end engages in the inner track 24e. Finally, if neither of the windings is energized, the finger remains vertical and engages in the central track 24a.

The electromagnet 28 only controls the adjustment pivoting of the fingers 8, while the latter are free to turn, the pole surfaces 32 acting on the fingers 8 by magnetic adhesion.

When one of the fingers 8 reaches the radius 26 (FIG. 4), its top end 23 engages in one of the grooves 22 in the plate 19 and the grooves are so devised that the end 23 is introduced into a different groove depending upon whether its bottom part 10 has been directed into the central track 24a or one or other of the side tracks 24b or 24C.

Within the angle of rotation A, which corresponds to the engagement of one of the fingers 8 in the plate 19 of the slide, the side tracks 24h and 24e` converge into the circular track so that the finger, if it had been moved, is returned into the vertical position during its engagement with the plate 19. The finger 8 thereby displaces the slide 16 the distance D in either direction. The pitch of the teeth formed by the grooves 22 in the plate 19 is equal to the distance D and the fingers `8 can thus move the slide 16 in either direction per pitch `length D.

In the position of the slide 16 shown in FIG. 3, the fingers 8 in the vertical position are made to pass into the central groove 22d and the main pinion 20` is situated at the center of the table 1 in register with a circular recess 33 formed at the center of the latter.

When the slide 16 is made to move stepwise to the right or left, the main pinion 20 can be made to run on four circular tracks on the top of the table as shown at C1, C2, C3 and C4 in FIGS. l and 5, being situated on either side of the table center O depending upon the direction of movement of the pinion from the point O.

Within the angle A corresponding to actuation of the slide 16 and extending over 1/12 of a circle, the central track 24a of the groove 24 has the shape of an arc of a circle having at its center the center of rotation of the table 1, while the two side tracks 24b and 24C are segments of two Archimedean spirals 34 and 35 of the same pitch equal to twelve times the distance D.

Since the angle A is 30 and the tracks 24b and 24C are segments of a true spiral of a pitch equal to 12D, the main pinion 20 can be passed between the different circular tracks spaced by the distance D so that its point of theoretical contact with the table is inscribed on the latter in accordance with twelve ascending spirals or twelve descending spirals depending upon whether the pinion is moved away from or approaches the point O.

By the very definition of a true spiral, the pinion runs on the plate without any slip and the theoretical point of contact is inscribed in accordance with such a spiral at a speed of rotation which varies linearly if the table is rotated at a constant speed.

To obvate any slip in the rotation between the table 1 and the pinion 20, the top surface of the table comprises a special toothing with which the pinion toothing constantly meshes. The plate toothing is described hereinafter with reference to FIG. 5.

The pinion 20 comprises twenty-four pointed teeth and on the outer circle C4 the plate 1 is formed with ninetysix recesses K1, K2, K3 etc. shown diagrammatically by circles and forming a toothing having the same circumferential pitch as that of the pinion.

Over the circle C3, the table toothing comprises seventytwo recesses shown diagrammatically at L1, L2, L3 etc., while over the circles C2 and C1 it comprises respectively forty-eight recesses M1, M2, M3 etc. and twenty-four recesses N1, N2, N3 etc., also shown diagrammatically by circles.

Consequently, on each rotation of the table through one revolution, the pinion 20 engaging in the recesses rotates respectively through vfour, three, two and one revolutions, depending upon whether it is situated on the circle C4, C3, C2 or C1.

When the pinion 20 is made to move from the circle C4 to the circle C3, while its plot on the plate has the form of a spiral Sd1 (FIG. 5), successive teeth of the pinion 20 progressively engage, as seen hereinbefore, in six recesses P1, P2, P3, P4, P and P6 shown diagrammatically by circles and dividing the spiral segment contained between the circles C4 and C3 into seven equal parts.

To pass from the circle C3 to the circle C2, the pinion 20 engages with four recesses Q1, Q2, Q3 and Q4, which dived the corresponding spiral segment into live equal parts.

Finally, to pass from the circle C2 to the circle C1, the pinion co-operates with two intermediate recesses R1 and R2 which divide the corresponding spiral segment into three equal parts.

Since a plurality of teeth of the pinion 20 simultaneously remain in engagement with the teeth of the table 1, clearance recesses are provided on each side of the recesses of the spiral, two such clearance recesses being provided upstream and two downstream of each recess of the spiral. Circles T1, T2, T3 and T4 denote the four clearance recesses framing the recess P3, and circles V1, V2, V3 and V4 denote the clearance recesses framing 'the recess P4 off the spiral. It is also necessary for the recesses involved in the engagement during the lateral displacement of the pinion to be extended in an approximately radial direction to allow for the lateral displacement of the pinion.

This clearance is obtained by combining the radially contiguous recesses in continuous grooves. Thus the recess P4 is formed by the central part of a groove W4 whose end parts each form two clearance recesses corresponding to the recesses P2 and P3 on the outside and P5 and P6 on the inside.

For the descending spiral Sdl in question there is therefore a series of grooves indicated over the entire length of the spiral and each covering tive recesses shown diagrammatically by a circle. These grooves are continuous and the circles diagrammatical'ly representing the individual recesses are shown only to facilitate an understanding of the engagement.

The toothing is constructed in the same way for all the spirals concerned, twelve ascending spirals (Sml to Sm12) and twelve descending spirals (Sdl to Sd12). FIG. 5 shows the grooves relating to the descending spiral Sdl, on the one hand, and on the other hand all the grooves relating to the 30 sector contained between the start K9 of said spiral Sdl and the start K1 of the preceding descending spiral Sdtl. The teeth on the plate are simply a repetition of the teeth on this sector twelve times.

It will be noted that the various grooves are sometimes formed in continuation of one another or by partial superimposition, more particularly near the circle C1. Since a plurality of pinion teeth are always simultaneously engaged in different grooves of the plate, the engagement nevertheless remains constantly determined even in the most involved zone of the table.

It should be noted that the grooves will, for example, have a V-shaped cross-section so that the engagement effect is still obtained in the case of partial superimposition of the grooves.

The twenty-four grooves relating to the inner circle C1 lead into the central circular recess 33 of the table 1 but it should be noted that only twelve of these grooves correspond to the spirals in question. Since the teeth could not be formed on the excessively reduced space available at the centre of the table, the rotation of the pinion 20 on its passage from the circle C1 to ,the centre point O or vice versa is obtained by an auxiliary guide device formed by the auxiliary pinion 21 and a guide cam 37 (FIG. 2).

The auxiliary pinion 21, which has the same diameter as the main pinion 20, has only twelve teeth (whereas the pinion 20 has twenty-four teeth). It is so secured on the shaft 14 that one of its twelve teeth is in the upper position when a tooth of the pinion 20 situated in the bottom position leaves the corresponding groove of the table 1 on the operation of the slide 16 which causes the pinion 20 to move from circle C1 to the centre O.

The cam 37 is formed by a plate suspended from the bottom end of a rod 38 mounted slidably in a support 39. A stop nut 40 limits the downward movement of the plate and a spring 41 tends to hold it in the bottom position illustrated while a transverse pin fitting in a slot of the support holds it in a predetermined angular position without preventing its limited lifting movement against the action of the spring (FIG. 2).

FIG. 7 is a bottom plan view of the cam 37 and a circle 42 diagrammatically represents the tooth of the pinon 21 in the top position when a bottom tooth of the pinion 20 leaves the groove of a descending spiral of the table surface on the edge of the recess 33 in the latter.

Displacement of the slide 16 brings the tooth 42 into a groove 43 in the plate, the outline of this groove being so devised as to turn the auxiliary pinion 21 on the passage of the tooth from the position shown at 42 to the position shown at 44, in the same way as if the main pinion 20 had continued its path in contact with the table surface in accordance with a line forming a continuation of the spiral on the latter.

If the slide 16 remains stationary in the central position of the pinion 20 shown in FIG. 3, in which the tooth of the auxiliary pinion is at 44, the shaft 14 remains stationary. If the slide 16 continues its displacement, the tooth of the auxiliary pinion follows a groove 45 which causes this pinion to turn in the opposite direction so that the main pinion 20 engages in the groove of the corresponding ascending spiral when it reaches the other side of the recess 33.

On the other hand, if the slide 16 is moved in the reverse direction, the tooth does not enter the groove 43 but engages in a groove 46 which progressively starts the pinion in the same direction as before so that it can reengage the circle C1 in accordance with the next ascending spiral. During this return movement, the tooth is compelled to follow the groove 46, because the opening of the groove 43 at 47 is shallower than the groove 46. As a result of the resilient suspension of the cam, the tooth always follows the deepest groove and the various branches are so devised as to ensure the above-described required displacements thus avoiding any ambiguity as a result of the crossing of the grooves. The auxiliary pinion 21 engages the cam 37 simultaneously by two teeth so that the outline of the grooves is duplicated as will be seen in FIG. 7.

The small number of teeth on the auxiliary pinion 21 enables the number of grooves inthe cam 37 to be reduced so that the latter has the necessary room although its usell length corresponds to the diameter of the table recess If the shaft 6 is driven at a constant speed, the shaft 14 driven by the wheel 20 can also deliver a base speed v1, corresponding to rotation of the wheel on the inner track C1, or three higher speeds v2=2v1, v3=3v1 and v4=4v1, corresponding to the other circular tracks. There is also a stop position corresponding to an output speed vo=0 and four other positions corresponding to the same speeds lbut in the opposite direction.

In a curve plotter, the output shaft 14 can control the movements of a plotter along a coordinate axis and the electrical signals transmitted to the control electromagnet 28 producing the changeover from one speed to another during a predetermined time corresponding to the rotation of the plate through 1/12 of a revolution.

Thus the electrical signals correspond to positive or negative speed variations occurring at specific intervals of time between which the displacement continues at constant speed. This programming method based on the transmission of data relating to the variations in speed (accelerations) requires much less data than methods based on the transmission of the coordinates of the points 7 or speeds. However, it requires the use of digital integrators having perfect and permanent agreement, of the type described hereinbefore.

In other applications, the shaft 6 may be driven at a variable speed. Similarly, in variant forms, the actuation of the fingers 8 by electrical control means (electromagnetic or the like) may occur While the fingers are engaged in the grooves of the slide 16. In this connection it should be noted that the teeth on the plate 19 of the slide have clearance portions 48 and 49 to the left and right of the end grooves 22a and 22g (FIG. 3).

In this way, erroneous actuation of the fingers by the electromagnetic control device cannot bring the pinion 20 out of the outer path C4.

In variants, in order to avoid the passage to the centre of the table, various arrangements shown diagrammatically in FIGS. 8, 9 and l0 may be used.

In the embodiment shown in FIG. 8, a toothed table 50 co-operates with two output pinions 51 and 52 mounted on a common slide 53. These pinions are coupled to two separate shafts 54 and 55 which are coupled to one another by a differential gear shown diagrammatically at 56` the output shaft being shown at 57. When the two pinions are at an equal distance from the centre of the plate, the output shaft 57 does not rotate because the two pinions rotate at the same speeds but in opposite directions. Depending upon whether the slide 53 is moved in one direction or the other, the output shaft will rotate in one or other direction.

In the variant shown in FIG. 9, a differential gear 58 is provided between a radially movable pinion 59 and a xed reference pinion 60 driven 'by the table.

Finally, in the embodiment shown in FIG. l0, two output pinions 61 and 62 drive two independent shafts 63 and 64 connected by a differential 65. No rotation of the output shaft 66 of the differential is obtained when the two pinions 61 and 62 both occupy the same inner circular track on the plate (FIG. c), while the output shaft 66 is made to turn in one or other direction depending upon whether one or other of the pinions is moved laterally (FIGS. 10a and 10b).

In variants of the apparatus (not illustrated), the table may be of conical shape. The teeth on the table and wheel may also co-operate if necessary through the agency of an intermediate transmission member, e.g. an intermediate pinion or chain.

We claim:

1. A digital integrator comprising a table having a surface provided with teeth, means mounting said table for rotation about an axis, a toothed wheel having teeth for meshing with the teeth of said table surface, and means mounting said toothed wheel for engagement with said table surface and for displacement radially of the axis of rotation of said table, wherein the improvement comprises a plurality of concentric circular toothed tracks of different diameters formed on said table surface and at least two toothed transfer tracks inclined in opposite directions formed on said table surface, said transfer tracks interconnecting said concentric tracks thereby permitting passage of said toothed wheel from one of said circular tracks to another, the teeth of said circular tracks and of said transfer tracks being so arranged that rotation of said toothed wheel engaged on said tracks remains constantly proportional to the distance of said toothed wheel from the axis of rotation of said table both on said circular tracks and along said transfer tracks.

2. An integrator as claimed in claim 1, comprising means for controlling the radial displacement of said toothed wheel along said transfer tracks.

3. An integrator as claimed in claim 2, wherein said control means comprise at least one actuating member borne by said table for rotation therewith and said toothed wheel is carried by a grooved slide movable radially of 8 the axis of rotation of said table, each said actuating member engaging a groove of said slide over a limited arc of the circular path described by said actuating member.

4. A digital integrator comprising,

a table having a surface provided with teeth,

means mounting said table for rotation about an axis,

a toothed wheel having teeth for meshing with the teeth of said table surface,

means mounting said toothed wheel for engagement with said table surface and for displacement radially of the axis of rotation of said table,

a plurality of concentric circular toothed tracks of different diameters formed on said table surface,

at least two toothed transfer tracks inclined in opposite directions formed on said table surface, said transfer tracks interconnecting said concentric tracks thereby permitting passage of said toothed wheel from one of said circular tracks to another,

the teeth of said circular tracks and of said transfer track being so arranged that rotation of said toothed wheel engaged on said tracks remains constantly proportional to the distance of said toothed wheel from the axis of rotation of said table both on said circular tracks and along said transfer tracks,

said control means comprise at least one actuating member borne by said table for rotation therewith,

said toothed wheel being carried by a grooved slide movable radially of the axis of rotation of said table,

each of said at least one actuating member engaging a groove of said slide over a limited arc of the circular path described by said actuating member, and

an electromagnet disposed adjacent to the path of said actuating member for displacing said actuating member when energized.

5. An integrator as claimed in claim 4, wherein said electromagnet is disposed upstream of the limited arc of the path of said actuating member over which said member engages said slide, and cam means are disposed to co-operate with said actuating member while it is engaged with said slide, said cam means acting on said actuating means in dependence upon the position previously irnparted to said actuating member by said electromagnet.

6. An integrator as claimed in claim 4, wherein said electromagnet has a pole surface inclined in the direction of movement of said actuating member and acting on said actuating member by electromagnetic attraction.

7. A digital integrator comprising,

a table having a surface provided with teeth.

means mounting said table for rotation about an axis,

a toothed wheel having teeth for meshing with the teeth of said table surface,

means mounting said toothed wheel for engagement with said table surface and for displacement radially of the axis of rotation of said table,

a plurality of concentric circular toothed tracks of different diameters formed on said table surface.

at least two toothed transfer tracks inclined in opposite directions formed on said table surface,

said transfer tracks interconnecting said concentric tracks thereby permitting passage of said toothed wheel from one of said circular tracks to another, the teeth of said circular tracks and of said transfer tracks being so arranged that rotation of said toothed wheel engaged on said tracks remains constantly proportional to the distance of said toothed wheel from the axis of rotation of said table both on said circular tracks and along said transfer tracks,

said table includes a central zone having no teeth within the innermost circular track, and

an auxiliary guide device to control rotation of said toothed wheel when it is within said central zone.

8. An integrator as claimed in claim 7, wherein said 9 auxiliary guide comprises an auxiliary wheel provided with teeth and coupled to said toothed wheel engaging said table surface and guide means for engagement by said auxiliary toothed wheel, said auxiliary wheel being brought into engagement with said guide means when said toothed wheel enters the central zone of said table surface.

9. An integrator as claimed in claim 8, comprising a slide interconnecting said toothed Wheel and said auxiliary wheel and a shaft extending radially of the axis of rotation of said table, said toothed wheel and auxiliary wheel being mounted on said shaft for rotation therewith.

References Cited UNITED STATES PATENTS 4/ 1954 Tinus 74--55 2/ 1959 Shephard 74-55 7/ 1964 Rabenau 74-55 WILLIAM F. ODEA, Primary Examiner W. S. RATLIFF, JR., Assistant Examiner U.S. Cl. X.R. 

